Texas astronomers find most distant known galaxy

A Texas-led team of astronomers has spotted the most distant known galaxy in the universe.

The observation of the young galaxy, which formed only about 700 million years after the Big Bang, offers scientists an unprecedented glimpse of the early universe.

The finding, published Wednesday by astronomers from both the University of Texas and Texas A&M, also showcases how telescopes have united the two historical rivals.

Not only did leading astronomers from both institutions work together to make this discovery, they are also collaborating on construction of a new, giant telescope that will afford still clearer views of the early universe.

The discovery wouldn't have been possible without NASA's decision to perform a final servicing and upgrade mission to the Hubble Space Telescope in 2009.

During this spaceflight, astronauts made several improvements, including the addition of a new wide-field camera.

This added the capability for the telescope to see into the near-infrared portion of the spectrum - light with a slightly longer wavelength than that of visible light. This light, it turns out, is very useful for studying distant galaxies.

Using this new Hubble camera in 2012 a team of astronomers identified a number of interesting objects they wanted to study further with ground-based telescopes. Although Earth-bound telescopes do not have the benefit of being located above Earth's blurring atmosphere, they do have larger mirrors than Hubble.

On two nights in April, Finkelstein and his team got time on one of the two largest telescopes in the world, the 33-foot Keck telescopes in Hawaii.

The astronomers patiently took data on about 40 objects that the Hubble data indicated might be galaxies that formed in the early universe.

To the surprise of the astronomers, only one of them was a hit.

"We were excited and disappointed at the same time," Finkelstein said.

Oh, what a hit it was

But oh, what a hit. It turns out that the object was a galaxy now nearly 30 billion light-years from Earth.

A paper describing the discovery was published Wednesday in Nature.

Astronomers have never observed a galaxy that's older or more distant than this one. Finding objects this old, when galaxies and stars were only first beginning to form, is essential if scientists are to piece together the story of how the universe developed.

What's surprising is that only one of the 40 objects on their list turned out to be a distant galaxy. Where were the others?

The answer may have to do with a cosmic fog - pervasive hydrogen gas that existed throughout the universe during the first 500 million to 700 million years of the universe's existence. This neutral hydrogen effectively shrouds most early galaxies from existing telescopes.

So what burned off this cosmic fog? It was actually the first really big and bright stars - about 20 to 100 times the size of our sun.

These stars emitted very energetic light particles that collided with the electrons zipping around hydrogen atoms. When these photons have enough energy, as those coming from very bright stars do, they strip off the electrons.

The time when this process occurred is called reionization, and the discovery of this very old galaxy is helping astronomers to understand when and how it occurred.

"One of the major goals of this whole research program is to identify this last main phase change," said Texas A&M astrophysicist Casey Papovich.

Happy mascots?

The Texas astronomers say that, with new additions to the Keck and Hubble telescopes, they are pushing those instruments to their limit. It will take newer, and larger, ground-based telescopes to probe deeper into the universe's mysteries.

To that end, Texas and Texas A&M are partners in an effort to build one of these, the 80-foot Giant Magellan Telescope, that could begin operations as early as 2018.

With this telescope and its far greater ability to see faint objects, the Texas astronomers say they just might be able to see the earliest stars and galaxies that formed in the universe.